1. Field of the Invention
The present invention relates to a display apparatus having a display panel such as a plasma display panel (hereinafter, referred to as a PDP) of a matrix display system.
2. Description of the Related Arts
In recent years, in association with enlargement of a display apparatus, a thin-type display apparatus has been required and various thin-type display apparatuses have been put into practical use. As one of the thin-type display apparatuses, attention is paid to a display apparatus using an AC (alternating discharge) type PDP.
The PDP has: a plurality of column electrodes (address electrodes); and a plurality of row electrode pairs arranged so as to cross those column electrodes. Each of the row electrode pairs and the column electrodes is coated with a dielectric layer for a discharge space and they have a structure such that a discharge cell corresponding to one pixel is formed at a cross point of the row electrode pair and the column electrode. Since the PDP performs a light emission display by using a discharge phenomenon, each of the discharge cells has only two states, that is, a light emitting state and a non-light emitting state. A subfield method, therefore, is used in order to realize a halftone luminance display corresponding to an input video signal by the PDP. According to the subfield method, a display period of time of one field is divided into a plurality of subfields and the input video signal is converted into pixel data of the number of bits as many as the number of subfields every field. Each bit of the pixel data indicates the light emission or the non-light emission of a period of time of one of the plurality of subfields. The converted pixel data is once stored into a field memory every field. The corresponding bit of the pixel data is read from the field memory every subfield at the timing responsive to a sync signal of the input video signal. In the case of the bit to be light-emitted, the number of light emitting times corresponding to a weight of the subfield is allocated thereto, and the bit is light-emission driven (for example, refer to the Official Gazette of Japanese Patent Kokai No. 2000-259122).
In the display apparatus using the subfield method, in order to improve image quality of the halftone luminance display, there is a method whereby the number of subfields is increased. Since the number of bits of the pixel data which is stored into the field memory, however, also increases in accordance with the increase in the number of subfields, there is a problem such that a capacity of the field memory also increases.